1. Field of the Invention
The invention relates generally to testing of electronic systems, and more particularly to signal converters.
2. Related Art
Test instruments are known for testing many types of electronic units under test. For example, instruments to test printed circuit boards and other electronic assemblies are known. Though test instruments come in many forms, a test instrument contains circuitry to generate or measure a test signal. To fully test an electronic unit, the test instrument may be programmable to control multiple parameters of test signals that are generated or measured. In sophisticated instruments, parameters relating to both the magnitude and timing of test signals, for example, may be programmed. Accordingly, test instruments may be sophisticated electronic devices.
Test instruments may be used during multiple stages in the lifecycle of an electronic unit. Test instruments may be used to make repairs after the unit has been fielded. In this role, the test instrument may be used to identify defective components that may be replaced or to identify other corrective actions that might be taken. In other scenarios, test instruments may be used during manufacture of the electronic units. In this capacity, the instruments may be used to identify defects such that the results of testing may be used to impact the manufacture of a device by conditioning certain operations on the results of testing. For example, manufacturing steps that result in the unit being packaged and shipped to a customer may be performed only if testing on a unit indicates that the unit is working properly. If the tests indicate that the unit is not working properly, the unit may be diverted such that different operations to rework or scrap the unit are performed.
Regardless of the specific reason for conducting tests, test instruments may be connected to the units in different ways, depending on the nature of the unit under test. For example, in some scenarios, the test instrument may be connected to a unit under test through a test fixture that contains probes to make mechanical and electrical connection to test points within the unit under test. In other scenarios, a test instrument may be connected to operational inputs and outputs of the unit under test. For example, an electronic unit designed to be connected to other electronic units over a bus may be tested through a port on the electronic unit designed to connect to a bus. Regardless of the nature of the connection, the test instrument may be configured to generate and measure test signals as may appear on that type of connection.